An ever increasing use of petroleum products worldwide has brought with it a proportionate increase in the number of accidental (or deliberate) hydrocarbon oil spills in open bodies of water, rivers, harbors, lakes and oceans. Major spills such as those caused by marine accidents receive widespread notoriety and may have catastrophic effects on sea life and beach fronts. Unfortunately, major spills are distinguished only by their magnitude. Minor spills are more common and, while less deleterious, also receive little attention and clean up efforts. A typical oil spill is the discharge (accidental or deliberate) of from five hundred gallons to several hundred-thousand gallons or more of petroleum product. The materials most frequently spilled are crude oil and heavy diesel oil. Such spills float for extended periods of time, and their residue often washes up on the beaches. Spills of lighter petroleum products such as gasoline or kerosene ultimately evaporate; however the heavier hydrocarbons such as crude oil oxidize or otherwise react with air and water to become more viscous, tar-like liquid. A fully developed petroleum product spill constitutes a thin slick or discontinuous film about 1.5 mm. or less in thickness of this tar like material having a specific gravity of from about 0.8 to 1.0 and drifts freely on the surface of the water, being carried about by wind, wave and current.
At the least, oil spills are a serious pollution problem. Large spills can be disastrous to birds and sea life. Even small spills can foul beaches. The desirability of mopping up oil spills has long been recognized. Unfortunately doing so is very difficult when the oil spill is over a wide area as a thin film, often less than a quarter inch thick, even in an emulsified form with the water. Removing oil from a body of water is difficult and very expensive.
Earlier methods proposed for oil spill recovery generally utilize absorbent pads, siphon off the oil with machines, or treat the oil with detergents to emulsify the oil. All have been used with very limited success. Several inventions in the field describe oil recovery methods involving the use of magnetic particles. U.S. Pat. No. 3,635,819 to Kaiser describes a ferrofluid containing an oil-soluble, water-insoluble, surfactant. The magnetic particles utilized in the ferrofluid have particle diameters in the order of nanometers, which provides the property of manipulating the fluid with a magnetic field. These materials, however, fail to provide the increased affinity of the oil to the magnetic particles. U.S. Pat. No. 4,187,187, to Turbeville, discloses a method and apparatus for pollutant spill control having a synthetic, plastic substrate imbedded with non-abrasive, magnetic iron particles. The oleophilic substrate attracts the hydrocarbons of the pollutant spill, which are then removed from a body of water by the magnetic affiliation properties of the iron particles when introduced to a magnetic field. The substrate is flexible and may be wrung out for subsequent reuse, but is limited in applications on pollutant spills, due to its solid form design.